This book aims to find a workable interpretation of the non-appropriation principle that is compatible with both the existing international space law framework and the move of the private space industry towards the mining of asteroids and other celestial bodies. It does so by analysing the rules on the use of orbits as limited natural resources as a concrete indication of how space resources can be exploited by one user while respecting the non-appropriation principle and the interests of other users in space. This analysis is complemented by a thorough review of the meaning of property...